The present invention relates to an improved sound radiating structure, acoustic room and sound scattering method.
Heretofore, there have been proposed and known various methods for obviating sound or acoustic obstacles in concert halls, auditoriums or like facilities or acoustic rooms by scattering sounds. Among such known acoustic-obstacle obviating methods is one which is characterized in that sound scattering members, each having a mountain-shaped or semicircular section, are attached to wall surfaces of the hall or like facilities so that the projecting and depressed configurations formed by the sound scattering members can control directions of reflected sounds to thereby scatter the sounds. Another known example of the acoustic-obstacle obviating methods is characterized in that sound absorbing panels are attached dispersedly to the inner wall surfaces, ceiling surface, etc. of the facilities so that acoustic impedance can be varied to promote scattering of the sounds. Still another known example of the acoustic-obstacle obviating methods is characterized in that sounds are scattered using a sound scattering structure, such as a Shroeder-type sound scattering structure, which has a surface with grooves of different depths based on a random series.
However, in the first-mentioned conventional acoustic-obstacle obviating method characterized by attaching the sound scattering members of a mountain-shaped or semicircular section to the wall surfaces of the facilities, the sound scattering members, forming the projecting and depressed configurations, tend to have a considerably great thickness. Thus, the interior space of the facilities would be greatly sacrificed if such thick sound scattering members are attached to the inner wall surfaces of the facilities. Further, if the sound scattering members of the mountain-shaped or semicircular section are attached all over the inner wall surfaces of the facilities, the interior of the facilities would result in a uniform and monotonous outer appearance. However, the projecting and depressed configuration can not be changed as desired because the sound scattering effects are afforded by such a configuration, with the result that the degree of flexibility or freedom in choosing the design is significantly limited.
In the second-mentioned conventional acoustic-obstacle obviating method characterized by the sound absorbing panels dispersedly attached to the inner wall surfaces, etc. of the facilities so as to provide alternating sound absorbing and sound reflecting regions on the wall surfaces, the sound absorbing effects of a number of the sound absorbing panels, although arranged dispersedly, would undesirably deteriorate the necessary acoustic liveness in the interior of the facilities. Further, in order to expand the frequency bands where the sound scattering effects can be obtained, it is necessary to provide various types of sound absorbing panels. In addition, this method is not satisfactory in that the sound scattering effects afforded thereby are not sufficient.
In the third-mentioned conventional acoustic-obstacle obviating method characterized by using the structure (such as the Shroeder-type sound scattering structure) having a surface with grooves of different depths, the depths of the grooves have to be sufficiently great (in effect, mote than 30 cm) in order to achieve the sound scattering effects in low frequency bands as well. The increased depths of the grooves would require a greater thickness of the structure, so that the interior space of the facilities would be sacrificed to a greater degree. Further, where the Shroeder-type sound scattering structure is employed, it would greatly influence the architectural design of the facilities due to its unique shape. In addition, because the Shroeder-type sound scattering structure would absorb low-frequency sounds, it is not suitable for applications where great sound scattering effects are to be achieved in low sound pitch ranges.